A marine outboard engine generally comprises a stern bracket assembly that is fixed to the stern of a hull (boat) and to an outboard engine main unit incorporating an internal combustion engine, propeller and the like. The marine outboard engine is typically designed so that the steering angle and the tilt/trim angles of the outboard engine relative to the stern brackets (i.e. the steering angle and the tilt/trim angles relative to the boat) can be adjusted and modified as desired. The stern bracket assembly typically includes a swivel bracket carrying the outboard engine for pivotal movement about a steering axis that extends generally vertically, and a clamping bracket supporting the swivel bracket and the outboard engine for pivotal movement about a tilt axis extending generally horizontally.
Known tilt-trim subsystems typically comprise a tilt cylinder unit for swinging a swivel bracket through a relatively large angle to lift the lower portion of the outboard engine above the water level or, conversely, lower the outboard engine below the water level. Such subsystems may further comprise a distinct trim cylinder unit for angularly moving the swivel bracket through a relatively small angle to trim the outboard engine while the lower portion thereof is being submerged. One desirable characteristic of a tilt-trim subsystem would be to provide a slower rate of rotation during trimming to retain the propulsion unit in water for a longer interval during movement thereof through a predetermined angular trim range and thereafter to more rapidly elevate the propulsion unit from the water so as to reach a full tilt-up position. Unfortunately, previous tilt-trim subsystems, as suggested above, may require use of distinct tilt and trim cylinder units or have required use of fairly complex mechanical structures to somewhat meet the tilt-trim requirements of the propulsion unit. Previous subsystems have typically been bulky and cumbersome.
Therefore, there is a need for a tilt-trim and steering subsystem for a marine outboard engine that alleviates some of the drawbacks of prior art systems.